PLANT ECOPHYSIOLOGY

When plants are subjected to some form of stress, the behavior of stomata and photosynthesis is usually affected. For example, with water stress due to a lack of water in the soil, one of the immediate and most determining reactions in the plant is stomatal closure to control water loss. However, this closure of stomata leads to a decrease in photosynthesis as less CO₂ enters the leaves, and consequently, a reduction in plant growth and production in the case of crops.

In our service we offer measurements of photosynthesis and stomatal conductance rates performed with a portable infrared analyzer, from which we obtain information about the operational state of our plant. These measurements are fundamental in ecological and agronomic studies as they allow for the detection of differences between species or applied treatments.

Additionally, in our service we provide measurements of other variables related to the previous ones, such as the rate of mesophyll conductance to CO₂, electronic transport or photoinhibition, all through combined measurements of gas exchange with chlorophyll fluorescence.

Finally, our service also offers the performance of photosynthetic response curves to environmental variables such as light, CO₂ or atmospheric water vapor demand, from which interesting parameters like leaf photosynthetic capacity can be obtained.

To carry out all of the above, we have a wide variety of measurement chambers that will be used depending on the type of measurement requested:

The gas exchange measurements have the ISO 9001 Quality Certificate, guaranteeing that the entire measurement and analysis process is carried out correctly and that the final result is fully satisfactory and trustworthy for the client.

The measurement of sap flow in trees allows us to estimate the amount of water transpired by them and thus determine their activity and the presence of symptoms of water stress. Our technique is based on the heat pulse compensation method and consists of installing a heating needle in the xylem of the tree flanked by two probes with thermocouples, one upstream and one downstream of the transpiratory flow.

This technique, in addition to estimating transpiration, under certain conditions can also serve to estimate stomatal conductance automatically, which is innovative. Stomatal conductance is a very sensitive and reliable indicator of water stress and can be useful in irrigation management studies in Agriculture.

The use of this service also requires the use of a datalogger (see features on loggers in this same service).

Leaf turgor is one of the most sensitive physiological variables to water stress. It directly indicates the water status of the plant and, at the same time, other important variables such as stomatal conductance.

In our service, we have a technique that allows its in vivo estimation under field conditions using button-shaped sensors that are installed on the leaves and allow for the continuous and automatic measurement of the daily dynamics of turgor potential.

Numerous studies conducted in various species demonstrate that the measurements thus made are closely correlated with water potential and maximum stomatal conductance, allowing for the rapid and simple identification of water stress states.

Dataloggers are essential tools for automatically measuring and storing large volumes of data obtained with all types of sensors that measure variables in the atmosphere, plant or soil. They allow for the programming, processing, storage and transmission of measurements. In this way, they can be programmed to study plant responses to the variables we are measuring (soil water, atmospheric air demand, etc.). Up to 8 sensors can be connected to each datalogger and the number of measurements can be expanded up to 24 using a multiplexer (AM24T).

The measurement of leaf water potential is closely related to the water status of the plant and is a physiological variable considered a classic indicator of its stress level. The measurements are made with a Scholander chamber under controlled laboratory conditions connected to a video system that allows for the precise determination of the water equilibrium pressure of the sample.

The measurement of leaf osmotic potential is also closely related to the water status of the plant. It is a good indicator of the ability to acclimate to water stress and explains the maintenance of turgor at more negative water potentials. The measurements are made with a Wescor psychrometer under controlled laboratory conditions.

Trunk dendrometers and mini-fruit dendrometers allow for the measurement of micro-variations in their diameter due to transpiration during the day. Depending on the level of stress of the plant, these variations are greater or smaller. Trunk dendrometers also allow for the estimation of plant growth. Measurements are made with linear displacement meters.

Soil water is so important a measure as meteorological variables for understanding plant behavior. Depending on the availability of water in the soil, the plant will exhibit a higher or lower degree of stress. Soil water content is highly variable both temporally and spatially. Measurements will be made continuously with FDR-based probes that allow for measurements at different depths and up to one meter.